Security tip for vascular catheter and method of using same

ABSTRACT

A catheter ( 100 ) having a first lumen ( 110 ) having a first distal tip ( 112 ) and a second lumen ( 130 ) having a second distal tip ( 132 ). The first and second distal tips ( 112,132 ) include openable portions that are normally closed when undeflected by lumen fluid pressure imbalance relative to the blood pressure of the patient. The first lumen ( 110 ) has an openable portion, flap ( 114 ) that opens proximally into the first lumen when the first lumen is under negative pressure to withdraw blood from the vessel through the first lumen to be dialysed (but that can open distally into the vessel under positive lumen pressure to permit blood flow into the vessel). The second lumen ( 130 ) extends distally beyond the first distal tip ( 112 ) to its second distal tip ( 132 ), and its openable portion is several lip sections ( 135 ) that are normally closed against each other when undeflected but that open outwardly when the second lumen is positively pressurized during hemodialysis, permitting blood to return to the patient&#39;s vessel.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority from U.S. Provisional PatentApplication Ser. No. 60/679,098 filed May 9, 2005.

FIELD OF THE INVENTION

This relates to the field of medical devices and more particularly tocatheters and catheter assemblies.

BACKGROUND OF THE INVENTION

Hemodialysis catheters are implanted into the vasculature of a patient,and have proximal ends that extend from the patient and are connectableto and disconnectable from tubing of a hemodialysis apparatus. Suchcatheters are provided with a first lumen and a second lumen coextendingto respective distal tips that are carefully positioned at a selectedsite in a particular vessel of the patient, so that undialysed blood maybe withdrawn from the patient's vessel while dialysed blood may bereintroduced into the patient's vessel simultaneously, at respectivedistal tip openings of the lumens. The catheter lumens may becoextending separate catheters or may be dual lumens of a singlecatheter separated by a septum wall. The distal tips of the two lumensare generally staggered along the vessel such that blood being withdrawndoes not include any significant amount of dialysed blood that has beenreintroduced into the vessel at the more distal of the two distal tips.

When a particular dialysis procedure has been completed, the proximalends of the catheter are disconnected from the tubes of the hemodialysisapparatus, and the lumens are generally inactive until the subsequentdialysis procedure, although fluid medication or saline may be infusedinto at least one of the lumens, if and when desired, or a blood samplewithdrawn. However, blood is highly susceptible to coagulation and clotformation. The addition of a specific agent or locking solution to thecatheter or any extracorporeal blood-contacting surface can reduce theincidence of coagulation by interfering and/or inhibiting thehematological chemistry of blood and its interaction with syntheticmaterials, such as those from which catheters are made.

It is conventional, then, to introduce anticoagulant locking solutionssuch as heparin into an implanted catheter between hemodialysistreatments, to prevent clotting of blood within the catheter, and whichthen is withdrawn for the subsequent dialysis procedure. The bloodpressure of the patient effectively maintains the locking solutionwithin the catheter lumens by producing a pressure gradient against thelocking solution, even though the distal lumen tips are open structures.However, certain amounts of locking solution are known to enter thepatient's blood stream through the open distal tips. The amountsintroduced into the patient are not at a level to cause toxicity ordisrupt a patient's hematology.

It is desired to provide a catheter that will minimize or eliminate thesmall amounts of locking solution entering a patient's blood stream froman implanted catheter between dialysis treatments.

SUMMARY OF THE INVENTION

The catheter of the present invention includes a first lumen having afirst distal tip, and a second lumen having a second distal tip, whereinthe first and second distal tips having wall sections that are normallydisposed in a closed position but are each openable under fluidpressure. While both lumens have openable distal tip wall sections, thefirst distal tip has a wall section openable both inwardly and outwardlywhen the first lumen is subjected to negative pressure and positivepressure, respectively, relative to the blood pressure of the patient inwhom the catheter has been implanted, both the second distal tip has awall section openable only outwardly, that is, when the second lumen issubjected to positive pressure, and that closes when the second lumen issubjected to negative pressure.

In a preferred embodiment, the first lumen includes a flap section thatis joined at a connected section to the wall of the first lumen andextends to a free end that extends to the opposite side of the firstlumen to close the first distal tip when undeflected; the flap sectionis deflectable to open into the first lumen under negative pressureapplied to the proximal end of the first lumen, and is deflectable toopen outwardly from the first lumen under positive pressure applied tothe proximal end of the first lumen.

The second lumen extends a selected distance distally of the firstdistal tip to a second distal tip that is a generally rounded tip whenclosed, and the second distal tip is defined by an openable section thatis internally concave and may be formed by at least one slit cut into aclosed rounded distal tip after extrusion of the lumen, defining atleast two generally curved lip portions. The several lip portions areopenable outwardly under positive pressure applied to the distal end ofthe second lumen, and a closable together under negative pressureapplied to the second lumen. Near the second distal tip, in the sidewall of the second lumen are one or more openable side port sectionsthat are openable inwardly upon application of negative pressure to theproximal end of the second lumen.

The closable and openable sections of the first and second distal tipsections of the first and second lumens operate thusly: duringhemodialysis, negative pressure is applied to the first lumen and bloodis drawn from a patient's vessel into the first distal tip and throughthe first lumen; positive pressure applied to the second lumen whenblood enters the proximal end of the second lumen and separates theseveral lip portions at the second distal tip to re-enter the vessel.Were the reverse of the pressures to be caused by an incorrecthemodialysis connection, blood traveling into the first lumen would openthe flap to enter the vessel, while negative pressure on the secondlumen would close the several lip sections but open the side ports forblood to enter from the vessel. Between dialysis procedures, lockingsolution injected under low pressure into the catheter would fill bothlumens since the distal tips would be in their closed, undeflectedconditions, and when removed, blood from the vessel would enter bothdistal tips due to negative pressure on both lumens.

The present invention also includes a method for maintaining a lockingfluid in an implanted catheter; comprising the steps of: providing acatheter having a first lumen having a closed openable first distal endand a first proximal end, and a second lumen having a closed openablesecond distal end and a second proximal end; and injecting locking fluidinto the first and second proximal ends, wherein the closed first andsecond distal ends retain the locking fluid in the first and secondlumens. The present invention also includes a method of removing a locksolution from a catheter, comprising the steps of: providing a catheterhaving a first lumen having a closed openable first distal end and afirst proximal end, and a second lumen having a closed second distal endand a second proximal end, and at least one closed openable side portdisposed proximal of the second distal end; withdrawing the locksolution from the first proximal end, wherein the first distal end opensto allow blood into the first lumen; and, withdrawing the lock solutionfrom the second proximal end, wherein the at least one flap opens toallow blood into the second lumen

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate the presently preferredembodiments of the invention, and, together with the general descriptiongiven above and the detailed description given below, serve to explainthe features of the invention. In the drawings:

FIG. 1 is a side view, in section, of a distal end of a catheteraccording to a first embodiment of the present invention;

FIG. 1A is a distal end profile view, in section, of the catheter takenalong lines 1A-1A of FIG. 1;

FIG. 2 is an enlarged portion of the catheter taken along oval 2 of FIG.1;

FIG. 3 is an enlarged distal end profile view, in section, of thecatheter being operated in normal operation;

FIG. 4 is an enlarged distal end profile view, in section, of thecatheter being operated in reverse operation; and

FIG. 5 is an enlarged distal end profile view, in section, of a catheteraccording to a second embodiment of the preferred invention.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, like numerals indicate like elements throughout.Certain terminology is used herein for convenience only and is not to betaken as a limitation on the present invention. The term “distal” inmeant to describe the portion of a catheter according to the presentinvention that is inserted into a patient, and the term “proximal” ismeant to describe the portion of a catheter according to the presentinvention that remains exterior of the patient. The terminology includeswords specifically mentioned, derivatives thereof, and words of similarimport. The following describes preferred embodiments of the invention.However, it should be understood based on this disclosure, that theinvention is not limited by the preferred embodiments described herein.

Referring now to FIG. 1, a catheter 100 according to a first embodimentof the present invention is shown. The catheter 100 is a dual lumencatheter used for hemodialysis, wherein a first lumen 110 is used todraw blood from a vessel, such as the internal jugular vein, and asecond lumen 130 is used to return blood to the vessel. Further, whilethe second lumen 130 is used to return blood to the vessel, the secondlumen 130 may also be used to administer other fluids, such asmedication, to the vessel.

The inventive aspect of the present invention is the distal end 102 ofthe catheter 100. Consequently, the proximal end of the catheter 100,which typically includes: a hub at the proximal ends of the first andsecond lumens 110, 130; a pair of extension tubes extending proximallyfrom the hub, such that each extension tube is in fluid communicationwith one of the first and second lumens 110, 130 through the hub; and aluer connector on a proximal end of each of the extension tubes, is notshown, as the proximal end of the catheter 100 is known to those skilledin the art.

As seen in FIG. 1A, the first lumen 110 preferably has a D-shaped crosssection and the second lumen 130 preferably has a circular crosssection. However, those skilled in the art will recognize that the crosssections may be other shapes, such as “Double D”, “Circle C”, or otherlumen cross section configurations known to those skilled in the art.

A cross-sectional view of the distal end 102 of the catheter 100 isshown in FIG. 1. The first and second lumens 110, 130 are adjacent toand parallel to each other, and are separated from each other by aseptum 104. The second lumen 130 extends more distally than the firstlumen 110. The first and second lumens 110, 130 provide a smooth outersurface for insertion into a patient's blood vessel.

The distal end 112 of the first lumen 110 is enlarged in FIG. 2. Thedistal end 112 includes a flap 114 that extends obliquely from aconnected distal portion 116 to a free proximal portion 118. The flap114 closes the distal end 112 of the first lumen 110 to restrict fluidflow into or out of the first lumen 110. The connected distal portion116 is sufficiently pliable to allow the flap 114 to pivot about thedistal portion 116 to open the first lumen 110 during use, such as whenblood is either being drawn into the first lumen 110 or when blood isbeing expelled from the first lumen 110.

Referring back to FIGS. 1 and 1A, the second lumen 130 includes aninternally concave distal end 132 that is generally closed, but with aplurality of slits 134 that allow the distal end 132 to open underpressure from the second lumen 130. A generally curved lip portion 135is formed between each slit 134. As seen in FIG. 1A, four lip portions135 are formed, although those skilled in the art will recognize thatmore or less than four lip portions 135 may be formed. The shape of thedistal end 132 and the cut of the slits 134 allow fluid flow from thesecond lumen 130, through the distal end 132 and out of the second lumen130, but restrict fluid flow into the second lumen 130 from the distalend 132.

A plurality of side ports 136 are formed in the walls of the secondlumen 130 proximal of the distal end 132, with a flap 137 covering eachside port 136. Each flap 136 is preferably generally bulbous-shaped,with a distal connected end 138 and a free proximal end 140. In anunpressurized condition, each flap 137 closes off its respective sideport 136 to restrict fluid flow through the side port 136.

To manufacture the catheter 100, it is preferred that the lumens 110,130 are co-extruded according to procedures well known to those skilledin the art. The distal end 102 is inserted into a tipping machine thatforms the flap 114 over the distal end 112 of the first lumen 110 andforms the internally concave distal end 132 of the second lumen 130. Theflap 114 is then die cut to separate the free end 118 of the flap 114from the distal end and to allow the flap 114 to rotate about theconnected end 116. The slits 134 are also cut to form the lip portions135 in the distal end 132 of the second lumen 130. The flaps 137 arealso die cut to separate the free end 140 of each flap 137 from the wallof the second lumen 130.

In operation, the catheter 100 is inserted into the patient's bloodvessel according to techniques well known to those skilled in the art.When the proximal end of the catheter 100 is connected to an exteriordevice, such as a hemodialysis machine (not shown), blood flows from thevessel, through the catheter 100, to the exterior device, back throughthe catheter 100, and into the vessel again.

When the catheter 100 is correctly connected to the exterior device,standard operation of the catheter 100 is shown schematically in FIG. 3.Blood is drawn from the vessel V into the distal end 112 of the firstlumen 110 along the direction of arrow “A”. Blood pressure acting on theflap 114 pivots the flap 114 about the connected end 116 so that thefree end 118 travels generally proximally, opening the distal end 112and allowing the blood to flow into the first lumen 110. The blood thentravels to the exterior device, where the blood is processed.

The processed blood is then transported to the second lumen 130, wherethe blood enters the proximal end of the second lumen 130 and travelsthrough the second lumen 130 to the distal end 132 of the second lumen130. The pressure of the flowing blood against the distal end 132 of thesecond lumen 130 separates the lip portions 135 from each other, openingthe distal end 132, and allowing the blood to exit the second lumen 130along the direction of arrow “B”.

Occasionally, however, the catheter 100 may be incorrectly connected tothe exterior device such that blood is drawn into the second lumen 130and discharged through the first lumen 110. Operation of the catheter100 in this manner is shown schematically in FIG. 4. Blood is drawn intothe vessel V into the second lumen 130 through the flaps 137 in thedistal end 132 of the second lumen 130, as shown by the arrows “C” inFIG. 4. The flaps 137 open into the second lumen 130 to allow blood tobe drawn from the vessel V into the second lumen 130. The blood thentravels to the exterior device, where the blood is processed.

The processed blood is then transported to the first lumen 110, wherethe blood enters the proximal end of the first lumen 110 and travelsthrough the first lumen 110 to the distal end 112 of the first lumen 110to the flap 114. Blood pressure acting on the flap 114 pivots the flap114 about the connected end 116 so that the free end 118 travelsgenerally distally, opening the distal end 112 and allowing the blood toflow back into the vessel V, as indicated by arrow “D”.

In between treatments, when blood is not flowing through the catheter100, a catheter lock solution is injected into each of the first andsecond lumens 110, 130 from the proximal end of each of the first andsecond lumens 110, 130. Regarding the first lumen 110, the flap 114biases toward the closed position to close the distal end 112 of thefirst lumen 110 and prevent the lock solution from dispersing from thefirst lumen 110 into the vessel V. Regarding the second lumen 130, thelip portions 135 bias toward a closed position to close the distal end132, and the flaps 137 bias toward the wall of the second lumen 130 toclose the flaps 137 to prevent the lock solution from dispersing fromthe second lumen 130 into the vessel V.

To prepare the catheter 100 for a subsequent treatment, a syringe (notshown) is connected to the proximal end of the first lumen 110 and thelock solution is vacuum drawn from the first lumen 110 into thesyringes. The flap 114 biases toward the open position to allow bloodinto the distal end 112 of the first lumen 110 to make up for thenow-depleted lock solution. The syringe (or a subsequent syringe) isconnected to the proximal end of the second lumen 130 and the locksolution is vacuum drawn from the second lumen 130 into the syringe. Theflaps 137 open to allow blood into the distal end 132 of the secondlumen 130 to make up for the now-depleted lock solution. The syringe isremoved and the proximal end of the catheter 100 is able to be connectedto a hemodialysis machine.

In an alternate embodiment, shown in FIG. 5, a catheter 200 includes afirst lumen 210 and a second lumen 230 that have distal ends 212, 232,respectively, that are split apart from each other. A septum 204 thatdivides the first lumen 210 from the second lumen 230 splits off at apredetermined location to allow the distal end 212 of the first lumen210 to separate from the distal end 232 of the second lumen 230.

Optionally, as will be recognized by those skilled in the art, theseptum 204 may be splittable, to allow the distal end 212 of the firstlumen 210 to be split away from the distal end 232 of the second lumen230 at a variable location, as determined by the inserting physicianduring insertion of the catheter into the patient.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover modifications within the spirit and scope of thepresent invention as defined by the appended claims.

1. A catheter comprising: a first conduit defining a first lumen havinga first proximal end and a first distal end, wherein the first distalend comprises a first distal tip; a second conduit defining a secondlumen having a second proximal end and a second distal end, wherein thesecond distal end comprises a second distal tip; and a septum separatingthe first proximal end and the second proximal end, wherein the firstand second distal tips are normally closed and are openable in responseto relative pressure imbalances inside and outside the respective firstand second lumens.
 2. The catheter according to claim 1, wherein thefirst distal tip comprises a generally internally concave portion havingat least one slit cut generally longitudinally therein.
 3. The catheteraccording to claim 1, wherein the second distal tip comprises a flaphaving a connected distal portion and a free proximal portion.
 4. Thecatheter according to claim 1, wherein the first distal end extendsdistally of the second distal end.
 5. The catheter according to claim 1,wherein the first distal end has a generally circular cross section. 6.The catheter according to claim 1, wherein the second distal end has agenerally D-shaped cross section.
 7. The catheter according to claim 1,wherein the first conduit further comprises at least one port fluidlycommunicating the first lumen with an exterior of the first conduit. 8.The catheter according to claim 7, wherein the at least one port islongitudinally disposed between the first distal tip and the seconddistal tip.
 9. The catheter according to claim 7, wherein the at leastone port comprises a flap having a connected distal end and a freeproximal end.
 10. The catheter according to claim 1, wherein the distalend of the first lumen and the distal end of the second lumen aresplittable.
 11. The catheter according to claim 1, wherein the distalend of the first lumen and the distal end of the second lumen are split.12. A catheter assembly comprising: a first lumen having a first distalend with a first movable portion to at least partially close the firstdistal end; and a second lumen having a second distal end with a secondmovable portion to at least partially close the second distal end,wherein, when the catheter assembly is in use, fluid flow through thefirst lumen opens the first movable portion and fluid flow through thesecond lumen opens the second movable portion.
 13. The catheter assemblyaccording to claim 12, wherein the first movable portion differs fromthe second movable portion.
 14. The catheter assembly according to claim12, wherein the first movable portion is openable to allow fluid intothe first lumen.
 15. The catheter assembly according to claim 12,wherein the second movable portion is openable to allow fluid out of thesecond lumen.
 16. The catheter assembly according to claim 15, whereinthe second distal end comprises a movable portion to allow fluid intothe second lumen.
 17. A method of maintaining a locking fluid in animplanted catheter comprising: providing a catheter assembly having: afirst lumen having a closed first distal end and a first proximal end;and a second lumen having a closed second distal end and a secondproximal end; implanting the catheter assembly; and injecting thelocking fluid into the first end second proximal ends, wherein theclosed first distal end retains the locking fluid in the first lumen andthe closed second distal end retains the locking fluid in the secondlumen.
 18. A method of removing a lock solution from an implantedcatheter comprising: providing a catheter assembly having: a first lumenhaving a closed first distal end and a first proximal end; and a secondlumen having a closed second distal end, a second proximal end, and atleast one closed flap disposed proximal of the second distal end;implanting the catheter into a patient; introducing lock solution intothe catheter; withdrawing the lock solution from the first proximal end,wherein the first distal end opens to allow blood into the first lumen;and withdrawing the lock solution from the second proximal end, whereinthe at least one flap opens to allow blood into the second lumen.